Weird problem

Lately my car has been running good and bad. I don't know what is going on with it. I have a 99 5 Spd and sometimes it feels like it's running strong, but then all of the sudden, it feels like the motor has no pull. It seems to happen mostly up inclines or around a corner in 2nd gear. It idles good, I keep good gas in it, it has about 25k on the plugs, a new fuel filter and PCV, and it doesn't throw codes. I read somewhere that the knock sensor has a "ghost code". What the hell does that mean? Is that something I can check with a code reader at Autozone? The guy said the CEL had to be on to check it. I also wonder if it may be the transmission, but it doesn't slip out of gear and it doesn't make any noise (it's the quietest of any car I've had, maybe because I put synthetic oil in it). If anybody has experienced this type of feeling in their car and has suggestions, please let me know what you think. Thanks in advance.

man i just dont know ? has it always done this ? the weather is really hot now and can play a factor. is it running fast in the mornings but sluggish at miday ? could be the heat

Ghost code means there's a code but the CEL doesn't come on. My local Autozone checked my car even though the CEL wasn't on because they wanted to see just what a ghost code was. If you've noticed a decrease in performance like when you get on it but the car feels sluggish, your KS could be dead. How many miles do you have on the car?

~THT

Thanks Caesar and THT. Caesar, it is hot, and I wonder about that too, but I just can't convince myself that's the problem. THT, the car only has 56K on it so I don't know ik a KS would go bad that soon, but I've heard they are notorious for going out. One more thing, if it is the KS, should I try and install it myself? I've heard the Cali Spec Maximas are a pain to replace the sensor.